title: Induction of chromosome instability and stomach cancer by altering the expression pattern of mitotic checkpoint genes in mice exposed to areca-nut.
abstract: BACKGROUND
  There are strong indications for a causal association between areca-nut consumption and cancers. In Meghalaya, India, the variety of areca-nut is used as raw and unprocessed form whose chemical composition and pharmacological actions have been reported. Yet we know little on the initial pathway involved in areca-nut associated carcinogenesis since it is difficult to assess its effects on genetic alterations without interference of other compounding factors. Therefore, present study was undertaken in mice to verify the ability of raw areca-nut (RAN) to induce cancer and to monitor the expression of certain genes involved in carcinogenesis. This study was not intended to isolate any active ingredients from the RAN and to look its action.
  
  
  METHODS
  Three groups of mice (n = 25 in each) were taken and used at different time-points for different experimental analysis. The other three groups of mice (n = 15 in each) were considered for tumor induction studies. In each set, two groups were administered RAN-extract ad libitum in drinking water with or without lime. The expression of certain genes was assessed by conventional RT-PCR and immunoblotting. The mice were given the whole RAN-extract with and without lime in order to mimic the human consumption style of RAN.
  
  
  RESULTS
  Histological preparation of stomach tissue revealed that RAN induced stomach cancer. A gradual increase in the frequency of precocious anaphase and aneuploid cells was observed in the bone marrow cells with a greater increment following RAN + lime administeration. Levels of p53, Bax, Securin and p65 in esophageal and stomach cells were elevated during early days of RAN exposure while those of different mitotic checkpoint proteins were downregulated. Apoptotic cell death was detected in non-cancerous stomach cells but not in tumor cells which showed overexpression of Bax and absence of PARP.
  
  
  CONCLUSIONS
  Present study suggested (a) RAN induces stomach cancer, however, presence of lime promoted higher cell transformation and thereby developed cancer earlier, (b) perturbations in components of the chromosome segregation machinery could be involved in the initial process of carcinogenicity and (c) the importance of precocious anaphase as a screening marker for identification of mitotic checkpoint defects during early days.
authors.affiliation: Molecular Genetics Laboratory, Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya 793022, India.
authors.forename: Sillarine
authors.initials: S
authors.lastname: Kurkalang
authors.forename: Atanu
authors.initials: A
authors.lastname: Banerjee
authors.forename: Nitin
authors.initials: N
authors.lastname: Ghoshal
authors.forename: Hughbert
authors.initials: H
authors.lastname: Dkhar
authors.forename: Anupam
authors.initials: A
authors.lastname: Chatterjee
mesh_terms: D000818:Animals; D001114:Areca / Q000633:toxicity*; D043171:Chromosomal Instability / Q000187:drug effects* / Q000235:genetics; D005434:Flow Cytometry; D018816:Genes, cdc / Q000187:drug effects* / Q000235:genetics; D015151:Immunoblotting; D051379:Mice; D009754:Nuts / Q000633:toxicity; D010936:Plant Extracts / Q000633:toxicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000209:etiology* / Q000235:genetics; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics
chemical_list: D010936:Plant Extracts